A pierce nut is a female fastener component usually designed to receive a male component such as a threaded bolt to fasten two or more parts of an assembly together. The distinguishing characteristic of a pierce nut is the existence of a pilot collar on one face of the nut that, in the installation process, pierces a workpiece, such as a metal stamping, to remove a slug of material from the part and permanently fastens the nut to the stamping.
FIG. 1 shows a representative pierce nut 10, in this case having an octagonal metal body with peripheral wrenching surfaces 11. A pilot collar 12 of annular configuration extends axially from one face 13 of the nut and is centered around a threaded bore 14. Radial barbs 15 extend from the collar to the outside edges of the face 13.
FIG. 2 shows a typical installation of the pierce nut 10 in a “workpiece” 16 in the form of a metal stamping. The stamping may be steel, aluminum, or any of a variety of metals or other materials. In FIG. 2 the pierce nut 10 is shown in the installed condition wherein the pilot collar 12 has been driven through the workpiece 16 to produce a detached slug 18. In the case where a mating part is joined flush with the top surface of the workpiece 16, the collar may not drive through the workpiece 16 in which case the slug 18 may stay attached to the workpiece 16. The axial depth of the pilot collar is approximately, or less than the thickness of the workpiece which can be about 5.5 mm or less. In the final assembly, the bore 14 can receive a threaded male fastener such as a bolt entering the through bore from the lower side of the pierce nut 10 as shown in FIG. 2.